Hip replacement systems and methods

ABSTRACT

Disclosed are systems, methods, devices and surgical techniques for joint arthroplasty, including implant components that facilitate the position and implantation of a hip replacement using cutting guides and various femoral implant arrangements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/347,317 entitled “HIP REPLACEMENT SYSTEMS ANDMETHODS,” filed Nov. 9, 2016, which is a continuation application ofU.S. patent application Ser. No. 14/452,468 entitled “HIP REPLACEMENTSYSTEMS AND METHODS,” filed Aug. 5, 2014 and issued as U.S. Pat. No.9,492,184; which in turn claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/862,109 entitled “Hip Replacement System withUnique Femoral Prosthesis,” filed Aug. 5, 2013, the disclosures of whichare each hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The invention relates to improved orthopedic implants and surgicalimplantation procedures, as well as related methods, designs, systemsand models. More specifically, disclosed herein are improved methods,designs and/or systems for joint implant components that facilitate theposition and implantation of novel designs of hip replacementcomponents, including the use of patient-specific and/or patient-adaptedcutting guides.

BACKGROUND OF THE INVENTION

Total hip arthroplasty (also known as a hip replacement) is a commonlyperformed surgical procedure which involves removing part of a patient'ship joint and replacing the hip joint with metal and/or plasticcomponents. In a typical surgery, the surgeon will often plan theproposed surgical procedure, including estimating the location of theproposed bone cuts (osteotomy) on the templated radiographs before thesurgery. The location of the bone cuts on the femoral neck willdesirably partially determine the femoral prosthesis location and thepatient's ultimate leg length. It is therefore important in an existinghip surgery for the surgeon to make the femoral neck bone cut in theproper location to avoid limb length inequalities.

In general, the femoral bone must be prepared in the appropriate mannerwith the proper position and angle to accept the intended femoralprosthesis. The femoral prosthesis should also desirably be implanted inthe proper position and angle. Errors in either the preparation of thefemoral bone or the implantation of the femoral prosthesis can cause leglength discrepancies, offset discrepancies, leg rotational issues, hippain and/or hip instability issues. Typically, the femoral prosthesisshould be positioned down the center of the femoral canal. If thefemoral prosthesis is angled within the femoral canal such that thedistal tip of the femoral prosthesis is pointing toward the lateralfemoral cortex, then the femoral prosthesis is said to be in a varusposition. If the femoral prosthesis is pointing toward the medialfemoral cortex, then the implant is said to be in a valgus position.Ideally, the distal tip of the femoral prosthesis is pointing down thecenter of the femoral canal. If a femoral prosthesis is implanted in avarus or valgus position, then the implant may not rest at theappropriate level in the femoral canal, which can alter the leg lengthand offset. Femoral prosthesis that are implanted in a varus or valgusposition may also have a higher failure rate (aseptic loosening, thighpain, etc.) than a femoral prosthesis that is well sized and wellpositioned.

The native femoral anteversion is the angle formed between the femoralhead and the knee joint as looking down on top of the femoral bone.Desirably, the femoral prosthesis should fit this native femoralanteversion in most situations. Unfortunately, surgeons can accidentallychange the rotation of the femoral prosthesis during the preparation ofthe femoral bone, which can lead to bony impingement, fractures, and/orhip dislocations.

To date, surgical approaches for hip and knee replacements are oftenfundamentally different in terms of how they are attached to theirrespective bones. Knee replacements typically are attached to theexterior of the femoral and tibial bone like a cap on the end of thebone. In contrast, hip replacements are typically attached to the inside(i.e., endosteal surface) of the medullary canal. Of course, variousexceptions to this general rule exist, such as hip resurfacing (wherethe femoral component is attached to the exterior of the femoral bone)or knee revision procedures (where a femoral post may be employed). Butwhere the general rule applies, it aptly accounts for why femoralprosthesis can subside into the femoral canal after implantation whereasknee replacement and hip resurfacing prosthesis typically do notsubside. Moreover, the fit of the femoral prosthesis inside the femoralcanal is not as obvious to the surgeon with hip replacements compared toknee replacements, often because the implant is not visible. In manycases, an undersized or mal-aligned femoral prosthesis in traditionalhip replacements can settle further down the femoral canal once thepatient starts to walk on the implant.

Many hip replacements have a femoral prosthesis with a collar or ledgethat extends outward at the junction of metaphyseal and neck portion ofthe femoral prosthesis. If properly positioned, this collar could restagainst the femoral neck osteotomy so that the femoral prosthesis wouldresist subsiding down the femoral canal further than was expected. Insuch a design, the force transmitted across the hip joint could bepartially transmitted to the femoral bone through this collar. However,because in this design the femoral prosthesis still loads the femoralbone from inside the bone, the compression of the femoral component intothe femoral canal creates hoop stresses that can split or fracture thefemoral bone in much the same way as a log splitter can split apart alog.

Performing a joint replacement with patient specific instrumentsinvolves obtaining a pre-operative scan of the joint and thenmanufacturing tools or patient specific guides that precisely fit thebone involved in the joint replacement. The patient specific instrumentsform a reverse mold of the surface of the bone. When the patientspecific guide intimately contacts the femoral bone, the surgeon can beassured the bone cuts are being performed as planned from thepre-operative scan.

BRIEF SUMMARY OF THE INVENTION

The following invention incorporates various surgical techniques,including one or more unique components and techniques for guiding thesurgeon into making a femoral neck cut in an appropriate positionthrough a detailed cutting guide. The various features described hereincan be utilized to desirably ensure that the surgeon broaches orprepares the femoral canal with the proper anteversion angle as well asthe proper varus/valgus angle and proper depth. Various features can beutilized to ensure that the final prosthesis is implanted in the femoralcanal in the appropriate anteversion angle, varus/valgus angle, anddepth. Lastly, various features and embodiments disclosed and describedherein can be utilized to ensure that the torsional and compressiveforces on the femoral prosthesis are transferred to the femoral bone inan ideal fashion, including through a unique collar or similar featureon the femoral prosthesis that intimately contacts the endostealsurface, the osteotomy surface, and/or the periosteal surface of thefemoral neck at the level of the osteotomy and maximizes contact areabetween the collar and the bone, thereby desirably minimizing hoopstresses and/or torsion stresses, and alters to a desirable extent sometensile forces to compressive forces.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other objects, aspects, features, and advantages ofembodiments will become more apparent and may be better understood byreferring to the following description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1a depicts an anterior/posterior radiograph of an arthritic hipjoint and

FIG. 1b depicts a lateral radiograph of an arthritic hip joint;

FIG. 2 depicts an example of a standard femoral prosthesis with acollar;

FIGS. 3a and 3b depicts an AP and lateral radiograph of a hipreplacement;

FIG. 4a depicts a drawing of an AP view of a femoral guide thatreferences the proximal femoral bone;

FIGS. 5a and 5b depicts AP views of a femur with and without a femoralguide referencing the anterior femoral neck and other proximal femoralbone;

FIGS. 6a and 6b depicts views of the femoral bone after the femoral neckcut (osteotomy) has been performed and the femoral head removed;

FIGS. 7a and 7b depicts a femoral broach inserted into the femoral canalto prepare the bone to accept the femoral prosthesis;

FIGS. 8a, 8b and 8c depicts various exemplary embodiments of a femoralprosthesis implanted into the femoral canal;

FIGS. 9a, 9b and 9c depict the AP and lateral radiographs of a varietyof collar embodiments attached to an associated femoral prosthesis; and

FIGS. 10a, 10b, and 10c depict cross-sectional views of a standard flatcalcar reamer, a domed-shaped calcar reamer, and a hemispherical shapedcalcar reamer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1a depicts an anterior/posterior radiograph of an arthritic hipjoint and FIG. 1b depicts a lateral x-ray of an arthritic hip joint. Thepelvic bone (1) represents the superior portion of the hip joint, thefemur (10) represents the inferior portion of the hip joint, and thefemoral head (20) rotates in the acetabulum (25).

FIG. 2 depicts an example of a femoral component (27) with a collar(28). The femoral component is also known as a femoral stem or femoralprosthesis. The collar desirably prevents the femoral prosthesis fromsubsiding down the femoral canal because the collar rests of the calcarosteotomy (femoral neck cut) and prevents further translation of thefemoral prosthesis once the collar contacts the femoral osteotomy.

FIGS. 3a and 3b depicts AP and lateral radiographs of a typical hipreplacement. The acetabular component (30) has been implanted into theacetabulum. The femoral component or stem (50) has been implanted downthe femoral canal to the desired level. The prosthetic femoral head (40)has been attached to the femoral component (50) and articulates with theacetabular component (30). The femoral stem has a collar (60), whichrest against the femoral calcar bone (70).

FIG. 4a depicts an AP view of a femoral guide (80) that references asubstantial portion of the proximal femoral bone, such as either theanterior or posterior femoral neck. The guide could be patient specificor generic. As part of a pre-operative plan, the surgeon could usenon-invasive imaging data or other information to determine his intendedsurgical approach to the hip joint, and this intended approach woulddetermine whether the femoral guide would reference predominately theanterior femoral neck or posterior femoral neck. In both situations, thefemoral guide could reference a significant portion of the superior andinferior femoral neck and femoral head (20) as well.

The femoral guide (80) could contain a drill sleeve (110) that wouldaccept a drill bit (130) that could form an anterior to posterior (AP)hole (120) in the femoral bone at the intersection of the verticalfemoral cut guide (90) and the calcar femoral cut guide (100). This APhole (120) could later be used to ensure the femoral broach andprosthesis were implanted in the proper location. After the surgeondrilled this AP hole (120), they could likely leave the drill bit in thebone and then use the vertical cut guide (90) and the calcar cut guide(100) in the femoral guide to make the appropriate osteotomy in thefemoral bone. The drill bit could ensure that the saw blade did notextend beyond the intended osteotomy site, which could help preventgreater trochanter fractures from the saw blade extended beyond theintended osteotomy. Alternatively, the surgeon could drill the AP holeand then remove this femoral guide (80) and insert a different femoralguide (not shown) that had a cylinder that fit inside this AP hole and asaw guide that rested on the surface of the femoral bone to guide a sawblade to make the calcar and vertical cuts. This alternative approachcould include features (not shown) to create an improved fixation of thesaw guide to the bone to prevent the saw guide from moving while the sawcut the bone. This alternative approach could also drill a second holein the femoral neck or head for the main purpose of provided the sawguide with additional stability. The femoral head (20) could then beremoved from the femur.

The femoral guide could include one or more patient specific soft tissueprotectors (such as those disclosed in U.S. Utility patent applicationSer. No. 14/059,372, filed on Oct. 21, 2013, and US Provisional PatentApplication No. 61/716,571, filed on Oct. 21, 2012, the disclosures ofwhich are incorporated herein by reference in their entireties) alongthe intended path of the calcar osteotomy and superior femoral neck todesirably prevent the saw blade from inadvertently extended beyond thebone and cutting the hip capsule. The saw blade could be allowed tocontact the patient specific soft tissue protector once the saw bladeleft the femoral bone, instead of the soft tissue surrounding the hipjoint.

FIG. 5a depicts a view of a femoral guide (80) superimposed on theradiograph. The femoral guide (80) is shown referencing a large portionof the anterior femoral neck. The AP drill sleeve (110) is shownextending away from and attached to the femoral guide (80). The heightof the drill sleeve (110) could be patient specific such that the lengthof the drill bit (130) minus the height of the drill sleeve (110) wouldequal the width of the femoral neck. The drill bit (130) would thereforedrill through the femoral neck and desirably stop immediately after thedrill bit went through the opposite cortex when the head of the drillbit contacted the drill sleeve. The drill bit could be any diameter, butin various embodiments would likely be around 3-5 mm in diameter.

FIG. 5b depicts a view of a proximal femur after the AP hole (120) hasbeen drilled and the femoral guide removed. The purposed verticalfemoral osteotomy or cut (90) and the calcar femoral osteotomy or cut(100) are shown with the marked line, but the cuts have not beenperformed yet.

FIGS. 6a and 6b depict the femoral bone (10) after the femoral neckosteotomy has been performed and the femoral head removed. The anteriorto posterior (AP) hole (120) is shown at the intersection of the calcarosteotomy (100) and the vertical osteotomy (90) (see FIG. 5b ). This APhole could be located anywhere along the calcar osteotomy and does notnecessarily have to be located at the intersection. In this embodiment,this AP hole (120) will be utilized, at least in part, to ensure thatthe surgeon inserts the broach and femoral prosthesis in the correctanteversion, varus/valgus angle, and depth. Because the femoral head andneck have been removed, the medial and superior portions of the AP holehave been removed and the AP hole can accept an anterior to posterior(AP) bar (140) of the broach or prosthesis as they are inserted down thefemoral canal. The femoral neck osteotomy surface (121), and the femoralperiosteal surface (122) and the femoral endosteal surface (123) aredepicted at the level of the femoral neck osteotomy.

FIG. 7a depicts an exemplary femoral broach (130) inserted into thefemur (10) to prepare or machine the bone to accept the femoralprosthesis. If desired, the femoral broach could include an AP bar (140)that extended a few millimeters in the anterior and posterior directionaway from the broach much like a collar. This AP bar is shown in a morelateral position than a traditional collar, but could be locatedanywhere along the osteotomy. This AP bar would desirably be a similardiameter as the AP hole (120) and the drill bit (130). The broach and/orprosthesis would desirably be in the appropriate position when theanterior and posterior portions of the AP bar (140) aligned with theanterior and posterior portions of the AP hole (120). If the surgeontried to change the femoral anteversion, then the AP bar would desirablyno longer key into the AP hole (120). If the surgeon inserted the broachin a varus position, then the AP bar (140) could be medially to the APhole (120); the surgeon could realize this mistake and remove more bonefrom the lateral proximal femur to get the broach out of a varusposition and into the correct position.

The AP bar (140) on the broach could be removable or elevated on thebroach handle so that smaller broaches could be impacted further downthe femoral canal to prepare for the next larger broach size. Broachessmaller than the intended prosthetic size can typically extended downinto the femoral canal a few millimeters below the osteotomy level. TheAP bar (140) could be temporarily removed to allow these small broachesto fully prepare the femoral canal. The AP bar could also be removed sothat the surgeon could knowingly change the anteversion of the femoralbroach (and calculate the degree of change) if the intra-operativeinformation suggested a change was needed.

FIG. 7b depicts the broach without an AP bar. In this alternativeembodiment, the surgeon could also simply rely on a visual marker (145)on the broach, without any type of AP bar, to inform the surgeon aboutwhether the implanted broach position corresponded with the intendedbroach position. This visual marker shown in FIG. 7b can be a hollowcylinder (145) in the anterior to posterior direction. When the hollowcylinder lined up with the AP hole (120), the surgeon would know thebroach was in the correct position regarding the anteversion,varus/valgus, and depth. This hollow cylinder could be limited to justthe cross sectional area of the broach so that the hollow cylinder wouldnot interfere with the broach extending below the osteotomy level. Thebroach could therefore be impacted to its desired level based on thecontact between the broach and the medullary canal and endostealsurface. The visual marker (145) would desirably not prevent orinterfere with the broach reaching its appropriate and/or desiredposition. If desired, the hollow cylinder could accept a drill bit sothe surgeon could prepare this AP hole for the final prosthesis if therewas a difference between the first AP hole preparation and the hollowcylinder of the broach. This preparation might be necessary if thesurgeon implanted the broach further down the canal than thepre-operative plan predicted or if the surgeon deliberately oraccidentally changed the anteversion or varus/valgus position of thebroach relative to the plan.

The femoral broach could include various additional support features,including the use of a collar feature having vertical sides thatdesirably contact the periosteal bone (122) to ensure that the broachwas implanted in the femoral bone in the correct anteversion. Thesurgeon could also insert a patient specific cap on the femoral neckosteotomy surface (121) that referenced the AP holes (120). This patientspecific cap could narrow the width of the proximal femoral canal andhelp guide the broach into the correct anteversion. The broach couldalso have vertical markings along the anterior and posterior surface ofthe broach so the surgeon could align these markings with the AP hole(120) as the broach was inserted into the femoral canal to ensure theimplanted femoral anteversion matched the planned femoral anteversion.

FIGS. 8a and 8b depicts an exemplary femoral prosthesis (150) implantedinto the femur (10) with an additional collar feature (160 & 180)extending over the femoral neck osteotomy (121) and contacting theperiosteal surface (122) of the exterior surface of the femoral neck.The collar feature could be patient specific, modular, or just come inmultiple sizes. If the collar feature was patient specific, then theshape and size of the collar could be based off the pre-operative scanand manufactured as a continuous part of the femoral prosthesis tointimately fit the proximal femur. If the collar feature was modular,the surgeon would make a determination during the surgery as to thecorrect shape and size of the collar based on how the broach fit thebone. The surgeon could then attach a modular collar with theappropriate size to femoral prosthesis before or after it was implantedinto the femoral canal. Lastly, the device manufacture could offer theimplant with multiple different size collars (i.e. small, medium andlarge) and allow the surgeon to select the most appropriate sized collarduring the surgery.

The collar feature could have a flat horizontal portion (160) that couldcontact the femoral neck osteotomy (121) and vertical portions (180)that could contact the endosteal (123) and/or periosteal (122) surfacesof the femoral calcar and neck. The collar feature could extend over theneck osteotomy (121) and down the exterior (122) and interior surfaces(123) of the anterior and posterior femoral neck. The flat horizontalportion (160) of the collar feature could intimately contact the neckosteotomy. The axial force from vertical loading of the hip joint couldbe transmitted across the horizontal portion of the collar to thefemoral osteotomy surface (121). The horizontal portion (160) could bethe same shape as the cross sectional thickness of the proximal bone atthe osteotomy to prevent soft tissue impingement from an oversizedcollar. The vertical portion (180) of the collar feature couldintimately contact the periosteal surface (122) of the anterior andposterior femoral neck and calcar.

The torsion force between the femoral prosthesis and the femoral boneprimarily comes from the moment arm of the femoral head being loadedaway from the axis of the femoral prosthesis. In various embodiments,this torsion force could be transmitted through the vertical portions ofthe collar feature to the periosteal and endosteal surfaces of thefemoral neck. When torsion stress is applied between the femoralprosthesis and the femoral bone, a traditional prosthesis will typicallypush on just one side (anterior or posterior) of the endosteal bone. Thevarious embodiments disclosed herein, including the various featuresdescribed herein, provide an improved prosthesis with collar featuresthat can push on the endosteal surface on one side (i.e. anterior) andthe periosteal surface of the other side (i.e. posterior). This improvedtorsion stability could prevent implant loosening, intra-operativefracture, and postoperative fracture.

FIG. 8c depicts the AP bar (170) on the femoral prosthesis keying intothe AP hole (120) in the femoral bone to ensure that the femoralprosthesis (150) was in the correct anteversion, varus/valgusorientation and depth. The AP bar could be modular such that the femoralprosthesis could have a hole or similar attachment device in theprosthesis. The surgeon could select a length for the anterior andposterior portion of the AP bar based on how far the femoral broach wasfrom the anterior and posterior periosteal surfaces of the proximalfemur. The surgeon could then screw the 2 bars into the femoralprosthesis. In various alternative embodiments, the femoral prosthesiscould just have a single hole so the 2 bars could be placed through thefemoral prosthesis and screw into each other. The cross section of thebar and the hole in the femoral prosthesis could be round to allow forrotation, or could be provided in non-round (i.e., oval, triangular,square or other configurations—with corresponding unique spacingarrangements) to prevent and/or inhibit unwanted rotation.

The femoral prosthesis could include one or more collar features, one ormore collar features in combinations with the AP bar (FIGS. 8a and 8b ),or just the AP bar (FIG. 8c ). The collar feature could be continuousand connected with the AP bar or could comprise a separate tab that wasnot connected to the AP bar. If the collar feature did not attach to theAP bar, the AP bar (170) could have a vertical wall (175) on each of theanterior and posterior end of the bar that would extend in the inferiordirection and contact the periosteal (122) surface of the anterior andposterior femoral neck. The vertical wall of the collar feature couldalternatively start at the anterior bar and extend medially around thecalcar and then continue around to the posterior bar as shown in FIG. 8b. Both the vertical and horizontal portions of the collar feature couldbe continuous around the entire femoral neck osteotomy or just smalltabs in certain areas to allow better visualization of the contactbetween the collar and the femoral bone.

Traditional non-collared femoral prosthesis load the endosteal surfaceof the proximal femoral bone and create hoop stresses in the proximalfemur when the femoral prosthesis is driven into the bone duringimplanting the prosthesis or weight bearing. A femoral prosthesis with ageneric “collar” design loads the endosteal surface (123) of theproximal femoral bone and the osteotomy surface (121). The femoralprosthesis described here, in combination with the vertical portion ofthe collar feature, desirably allows the prosthesis to load theperiosteal surface of the proximal femur as well as the endostealsurface and the osteotomy surface. Loading the periosteal surface canhelp counteract and/or negate the hoop stresses that are generated fromloading the endosteal bone. This periosteal loading would desirablygenerate compressive forces in the proximal femur instead of tensileforces (hoop stresses). The material properties of bone are muchstronger in compression than tension, so loading the periosteal surfacecould decrease femoral calcar fractures.

FIG. 8a also depicts two suture holes (190) in the anterior andposterior portion of the collar. These suture holes could vary in numberand be used to reattach the posterior or anterior hip capsule back tothe femoral bone. These suture holes could also be used to reattach thegreater trochanter if a trochanter fracture occurred during the surgery.

FIGS. 9a, 9b, and 9c depict AP and lateral views of another exemplarycollar feature on an exemplary femoral prosthesis. The horizontalportion (160) and vertical portion (180) of the collar feature areshown. The AP bar (170) is shown. FIG. 9b depicts the exterior verticalcollar (200) that can be positioned to contact the periosteal surface(122) of the proximal femur and the interior vertical collar (210) thatdesirably contacts the endosteal surface (123) of the proximal femur.The vertical wall in FIG. 9b is desirably parallel with the axis of theprosthesis. FIG. 9c depicts an exterior vertical collar (215) that isdivergent to the axis of the prosthesis, which desirably allows foreasier insertion of the prosthesis over the femoral neck osteotomy. Thisdivergent wall could also load the periosteum of the proximal femur andneglect the hoop stresses that are typically generated from the normalprosthesis loading of the endosteal surface of the proximal femur. Thisarrangement also reduces and/or negates the need for a cerclage wire orother reinforcing arrangement on the proximal femur, as surgeons willoccasionally place a cerclage wire around the proximal femur tocounteract the hoop stresses on the bone associated with implanting theprosthesis in much the same way as this divergent wall could.

It should be understood that the collar features could be formed in awide variety of shapes and/or configurations, including shapes and/orfeatures that match and/or substantially conform, to varying degrees, tothe underlying anatomy that they contact. For example, the collarfeatures could comprise a hemispherical dome, an oval-shaped dome, atriangular box, a square or virtually any other shape that accomplishedsome or all of the features of the present invention. In variousembodiments, the bone-contacting surface(s) of the collar feature may benon-round and/or irregularly curved and/or otherwise shaped, so as todesirably reduce, prevent and/or inhibit rotation of the implant and/orpreferentially load the periosteal bone to varying degrees (instead ofthe endosteal side of the bone). It should also be understood that,where the collar feature and prosthesis are modular and/or separatelyformed, the collar feature could include a circular, non-circular and/orirregularly shaped opening formed therein to accommodate the femoralprosthesis.

FIGS. 10a, 10b, and 10c depict cross-sectional views of a standard flatcalcar reamer (220), of a reverse domed-shaped calcar reamer (250), andof a hemispherical or domed shaped calcar reamer (260). Flat calcarreamers are well known in the art. The male portion (230) of the femoralbroach (70) slides into the female portion (240) of the flat calcarreamer. The flat calcar reamer can rotate around the male portion andremove the necessary femoral bone to make a flat osteotomy surface (121)that maximizes contact between a flat collar and the femoral bone.

FIG. 10b depicts a cross-sectional view of a reverse domed-shaped reamerthat could rotate around the male portion of the broach and desirablyremove an amount of femoral bone to create a dome shaped osteotomysurface to maximize contact between a reverse dome shaped collar and thefemoral bone. If desired, the curvature of the reamer (i.e., modifyingthe proximal femur) could be slightly flatter than the curvature of theassociated collar feature, which could facilitate the collar contactingthe outside edge (i.e., periosteal edge) of the bone and loading thebone from the “outside-in.” FIG. 10c depicts a cross-sectional view of ahemisphere shaped reamer (260) that could rotate around the male portionof the broach and remove the necessary femoral bone to create a reversedome (i.e., a hemispherical dome) shaped osteotomy surface thatmaximizes contact between a hemispherical shaped collar and the femoralbone. The advantage of a dome shaped or reverse dome shaped osteotomysurface can be that axial compression of the implant and bone willdesirably increase the contact between the collar and the bone. Thetorsion stability of the implant could also be improved by thisarrangement. The anterior to posterior and medial to lateral stabilityof the implant could also be improved. The reverse dome shaped osteotomyin FIG. 10b with the dome shaped collar could also help minimize hoopstress from the femoral component loading the femoral canal. The domeshaped collar could help transform the tensile forces (i.e., hoopstresses) into compressive forces, and thereby help prevent calcarfractures that can be seen with implanting a standard femoral prosthesisor loading the femoral prosthesis during weight bearing movement. Thevertical portion of the patient specific collar could also help minimizehoop stresses in a manner similar to the cerclage wire does when it iswrapped around the proximal femoral bone, but without the need for suchan additional adjunct to the surgery.

If desired, the transitional spacing between the horizontal and verticalexterior surfaces of the collar could be rounded to prevent soft tissueimpingement.

The drawings and text above refer to the implantation of a femoralcomponent into a femoral bone for descriptive purposes only. Similarprinciples such as those described above could apply to other jointslike the knee, ankle, feet, shoulder, elbow, back and wrist, withvarious modifications to account for anatomical and loading differences.For example, the sutures holes (190) in the vertical portions of thecollar, shown in FIG. 8, could be applied to an implant for the shoulderjoint to allow for a repair of the rotator cuff tendons (supraspinatus,subscapularis, and/or anterior capsule).

INCORPORATION BY REFERENCE

The entire disclosure of each of the publications, patent documents, andother references referred to herein is incorporated herein by referencein its entirety for all purposes to the same extent as if eachindividual source were individually denoted as being incorporated byreference.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus intended to include all changes that come within themeaning and range of equivalency of the descriptions provided herein.

Many of the aspects and advantages of the present invention may be moreclearly understood and appreciated by reference to the accompanyingdrawings. The accompanying drawings are incorporated herein and form apart of the specification, illustrating embodiments of the presentinvention and together with the description, disclose the principles ofthe invention.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it will be readily apparent to those of ordinary skill inthe art in light of the teachings of this invention that certain changesand modifications may be made thereto without departing from the spiritor scope of the disclosure herein.

1. A femoral prosthesis for implantation into a resected proximal end ofa femur, the prosthesis comprising: a stem having a proximal end and adistal end, a collar portion for placement in a location adjacent theproximal end of the stem to engage at least a portion of the resectedproximal end of the femur, wherein the collar portion comprises aninterior surface sized and configured to be at least partially inintimate contact with an unresected outer surface of the femur when thestem is implanted into the femur; the stem further including analignment indicator that aligns with at least a portion of a hole formedinto a cortical wall of the femur when the stem is implanted into thefemur.
 2. The femoral prosthesis of claim 1, wherein the alignmentindicator comprises a generally cylindrical bar which extends outwardlyfrom the stem.
 3. The femoral prosthesis of claim 1, wherein thealignment indicator comprises a generally cylindrical bar which extendslaterally outward from opposing sides of the stem, wherein a firstportion of the alignment indicator aligns with a first portion of thehole and a second portion of the alignment indicator aligns with asecond portion of the hole.
 4. The femoral prosthesis of claim 1,wherein the alignment indicator comprises a bar which extends laterallyoutward from at least one side of the stem.
 5. The femoral prosthesis ofclaim 1, wherein the alignment indicator comprises a bar which extendscompletely through the stem.
 6. The femoral prosthesis of claim 1,wherein the alignment indicator is integrally attached to the stem. 7.The femoral prosthesis of claim 1, wherein the alignment indicator ismodularly attached to the stem.
 8. The femoral prosthesis of claim 1,wherein the alignment indicator includes a non-circular cross-section.9. The femoral prosthesis of claim 1, wherein the alignment indicator isremoveable from the stem.
 10. A femoral prosthesis for implantation intoa resected proximal end of a femur, the prosthesis comprising: anelongated stem having at least one opening formed therein, the openingextending generally transverse to a longitudinal axis of the elongatedstem, a first bar secured within the at least one opening, the first barincluding a first portion that extends outwardly from the elongatedstem, the first portion including an outer surface that engages with atleast a portion of the resected proximal end of the femur when the stemis implanted into the femur, wherein at least a portion of the firstportion is pre-operatively shaped to substantially match one or moreanatomical features of the patient.
 11. The femoral prosthesis of claim10, wherein the first portion includes an outer surface that keys intothe engaged portion of the resected proximal end of the femur.
 12. Thefemoral prosthesis of claim 10, wherein the at least one opening extendscompletely through the elongated stem.
 13. The femoral prosthesis ofclaim 12, wherein the first portion extends outwardly from a first sideof the opening, and the first bar further includes a second portionextending outwardly from an opposing side of the opening.
 14. Thefemoral prosthesis of claim 12, wherein the first bar is integrallyattached to the stem.
 15. The femoral prosthesis of claim 12, whereinthe first bar is modularly attached to the stem.
 16. The femoralprosthesis of claim 12, wherein the first bar includes a non-circularcross-section.
 17. The femoral prosthesis of claim 12, wherein the firstbar includes a circular cross-section.
 18. The femoral prosthesis ofclaim 12, wherein the first bar is removeable from the stem.
 19. Thefemoral prosthesis of claim 12, wherein the stem further comprises acollar portion for placement in a location adjacent the proximal end ofthe stem to engage at least a portion of the resected proximal end ofthe femur, wherein the collar portion comprises an interior surfacesized and configured to be at least partially in intimate contact withan unresected outer surface of the femur when the stem is implanted intothe femur.
 20. The femoral prosthesis of claim 19, wherein the collarportion includes a non-circular opening for accommodating the stem.